Question : how can I override the DateTime class to  add a custom method??

Hi, I want to override the default class System.DateTime to add a custom method, now i'm doing it this way (but doesn't works):

partial class DateTime
{
    public string ToStringFormated()
    {
        return base.ToString(AppConfig.dateFormat);
    }
}

i''m getting a incoherence accessibility error.

Answer : how can I override the DateTime class to  add a custom method??

DateTime is a class, you cannot derive a new class to override it.
The unique way is to use an extension method, but you require C# 3.0 for this (VS 2008), but still can use .net 2.0
Is that your case?